(1) Field of the Invention
This invention in general relates to a conveyor system for transporting objects from one station to another and, in particular, to the conveyor used in that system.
(2) Description of the Prior Art
Over the years numerous and various systems have been devised to transport or convey various objects of different sizes and shapes from one station to another. Those various conveying systems of which I am aware have been used in a wide variety of applications, for example, in commercial dishwashing operations, in cafeteria returns to transport trays of soiled dinner and tableware from the eating area to the kitchen, in ice cream factories to transport cartons of ice cream mix through the freezing zone, in hospitals where patients' food trays are made up, and in various work in process situations, i.e., assembly line operations.
One conveying system used in a commercial dishwashing operation and which was devised by the present inventor, along with Edward C. Grotto, is shown in U.S. Pat. No. 3,117,668, which issued Jan. 14, 1964. As disclosed in that patent, the conveyor is associated with a dishwashing machine in such fashion as to move racks of dishes through the washing machine from its entrance to its exit. The racks are supported on rectangular shaped dollies which in turn are supported by roller assemblies. These rollers ride in tracks located in a conveyor table providing a support for the system as well as a predetermined direction of travel.
Although the above conveyor system has been found quite satisfactory in many dishwashing operations, and it offers the advantage of better labor utilization in that it provides a means for returning empty racks, it is nevertheless attendant with certain disadvantages. In particular, this system does not allow cleaned racks of dishes to accumulate, once the racks exit from the dishwashing machines. The dollies on which the racks sit while being conveyed, are a fixed part of the conveyor. Thus, if the racks of clean dishes are not removed, they are returned by the conveyor to the point at which soiled dishes are loaded on to the conveyor. As a result, when the dishwashing machine is in operation, personnel must always be located at the discharge end to remove the rack of clean dishes.
A further disadvantage with the conveyor system disclosed in U.S. Pat. No. 3,117,668 is that, because it provides a return for empty racks, the lay-out of the system, e.g. oval shape in plan, necessarily involves lost space. The dollies require, for any particular installation, a certain minimum turning radius to maneuver the horizontally disposed track. Accordingly, the space requirements of this system are somewhat limiting in its use.
Another conveyor system developed by the present inventor, and which has been quite satisfactory in some dishwashing operations, is disclosed in U.S. Pat. No. 3,237,755, which issued Mar. 1, 1966. That conveyor system basically comprises an endless driven chain which comprises a plurality of links joined together. A set of main rollers project below the chain and roll along a table. The links have an upper extension on which a set of auxiliary rollers are mounted. The trays of dishes or other articles carried on the conveyor rest on the auxiliary rollers and are ordinarily carried along by the forward movement of the chain. If movement of the trays is in some way obstructed, however, the trays though stationary will roll on the auxiliary rollers so that the conveyor chain continues to move freely.
Although the system disclosed in U.S. Pat. No. 3,237,755 allows for accumulation of trays of dishes, etc., making unnecessary the immediate removal thereof, and allowing personnel to be absent from the discharge point momentarily, it does not provide for return of empty trays or racks to a loading point. This can only be accomplished by location of a similar system next to it, and positioned to operate in the reverse direction. Otherwise, empty racks must be manually returned to the loading station.
In the above, and other conveyor systems of which I am aware, particularly in food-service operations, not only is there a rather large initial cost involved in the installation, the cost of operating these conveyor systems is appreciable, as is the cost in their continual maintenance. In some installations, the drive mechanisms for the particular conveyor involved are necessarily rather large, and with todays ever increasing cost for electricity, this has become of some concern. Moreover, as these systems are made up of various mechanical components, these components require periodic adjustment and takeup due to wear. Other components require replacement as they wear or are broken or damaged.
In food-service operations, in particular, the conveyor table and conveyor are often dirtied by food from soiled plates, and other dinner and tableware, requiring constant cleaning with water. However, even though in some cases cleaning water sprays are incorporated in the system, cleaning is less adequate than desired, leaving a somewhat unsanitary situation. Cleaning of the conveyor is complicated in many cases as the conveyor return is often located in a relatively inaccessible place. As the conveyors are metal, when washed with water, they must then be subsequently lubricated to prevent rust. The lubricant is sometimes incorporated directly into the water spray cleaning mechanism. Washing and lubrication both naturally increase the overall cost of maintaining the system. In some cases, food particles build up on the conveyor table, or in the conveyor track resulting in a rather hard packed deposit, necessitating shut-down of the system for cleaning and removal, to avoid possible damage to the conveyor system.
Of critical concern today also is the saving of energy, as these costs keep ever increasing. In a dishwashing system, racks of soiled dishes are conveyed through the dishwashing machine wherein the dishes are subjected to various wash and rinsing cycles. Such a system is disclosed in U.S. Pat. No. 3,363,636 which issued Jan. 16, 1968 to Clyde R. Weihe, Jr., the applicant herein. In some installations, once the conveyor system is placed in operation, the various wash/rinse cycles continue their operation whether or not soiled dishes are being conveyed through the dishwashing machine. As a result, these systems are attendant with considerable waste of water and energy. Thus, it is a desire that in any dishwashing system each cycle be individually controlled with on and off operation, using rinse water, detergent water, etc., only when racks of soiled dishes are being conveyed through the dishwashing machine.